Meeting Abstract

P3.28  Sunday, Jan. 6  Identifying Abnormal Morphologies Associated with Chemical Challenges in the Brine Shrimp, Artemia franciscana NEUMEYER, C.H.*; GILDERSLEEVE, S.M.; COVI, J.A.; Univ. of Wisconsin-Stevens Point; Univ. of Wisconsin-Stevens Point; Univ. of North Carolina at Wilmington; Univ. of Wisconsin-Stevens Point covij@uncw.edu

Artemia franciscana is a commercially harvested model organism with a broad distribution and long history of use for biochemical, molecular, developmental and ultrastructural research. Early development in A. franciscana is classically divided into four stages: encysted embryo, emergence 1, emergence 2 and nauplius larva. These stages are separated by successive cuticular shedding, and are difficult to apply when aberrations in emergence are observed. Such developmental abnormalities have been documented in the presence of decreased levels of sodium bicarbonate or increased levels of heavy metals or toxins. Importantly, abnormal embryos resulting from divergent chemical challenges share similar gross morphological characteristics. Shared aberrant morphology may originate from a common problem. This appears to be an inability for the embryo to emerge from the first or second embryonic cuticle; embryos demonstrate structural characteristics in line with continued development in the confined space of the unshed embryonic cuticle(s). A modified nomenclature was developed to account for these shared aberrant morphologies. By providing a common set of characteristics, this more detailed description of morphology facilitated testing of the hypothesis that divergent chemical treatments result in common morphology by making it difficult to emerge from the embryonic cuticle. Embryos were dechorionated (viable embryos stripped of the proteinaceous chorion) and placed in 20, 25, 30, or 35ppt sterile artificial seawater for 72 h. Preliminary data demonstrate that conditions promoting aberrant morphology decrease hatch rates to a greater extent at higher salinities.